Methods for terminating optical fiber cables

ABSTRACT

A fiber optic cable system includes a fiber optic main cable having a strength member and a plurality of optical fibers extending therein within an outer cable sheath. A flexible longitudinally extending inner housing is positioned proximate the plurality of optical fibers on a section of the main cable having the outer cable sheath removed. At least one fiber optic drop cable has at least one optical fiber having an end portion extending outwardly from an end of the drop cable. The end portion is spliced together with an end portion of a corresponding at least one severed end portion of one of the plurality of optical fibers of the main cable to define at least one spliced together fiber portion coupling at least one of the plurality of optical fibers of the main cable to a corresponding one of the at least one fiber of the drop cable. A longitudinally extending outer protective housing extends over the section of the main cable having the outer cable sheath removed and the inner housing and the strength member. The outer protective housing has a first opening receiving the main cable and a second opening, longitudinally displaced from the first opening, receiving the main cable and at least one of the openings receiving the drop cable or cables.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 11/655,707 filed on Jan. 19, 2007 now U.S. Pat. No. 7,756,372,which claims priority from U.S. Provisional Application No. 60/775,614,filed Feb. 22, 2006, the disclosures of which are hereby incorporatedherein in their entirety by reference.

BACKGROUND OF THE INVENTION

The present invention relates to communication cable termination systemsand, more particularly, to optical fiber termination systems and methodsfor terminating the same.

An extensive infrastructure supporting telecommunication has beendeveloped, traditionally based upon copper wire connections betweenindividual subscribers and telecommunications company networkdistribution points. More recently, much of the telecommunicationsnetwork infrastructure is being extended or replaced with an opticalfiber based communications network infrastructure. The carrying capacityand communication rate capabilities of such equipment may exceed thatprovided by conventional copper wired systems.

As such, fiber optic cables are widely used for telecommunicationsapplications where high information capacity, noise immunity and otheradvantages of optical fibers may be exploited. Fiber cable architecturesare emerging for connecting homes and/or business establishments, viaoptical fibers, to a central location, for example. A trunk or maincable may be routed, for example, through a housing subdivision andsmall fiber count “drop cables” may be spliced to the main cable atpredetermined spaced apart locations.

A typical main cable may be installed underground and have multiple dropcables connected thereto, each of a hundred feet or more. Each of thedrop cables, in turn, may be routed to an optical network unit (ONU)serving several homes. Information may then be transmitted optically tothe ONU, and into the home, via conventional copper cable technology,although it also has been proposed to extend optical fiber all the wayto the home rather than just to the ONU. Thus, the drop cables may servegroups of users, although other architectures may also employ a maincable and one or more drop cables connected thereto.

Unfortunately, the fibers within the main cable must typically beaccessed at the various drop points and spliced to respective dropcables after the main cable has already been installed. Accessing themain cable for splicing generally requires careful preparation of themain cable including removing a portion of the cable sheath, andidentifying and separating out predetermined fibers from within thecable without disturbing adjacent fibers. The separated fibers may thenbe spliced and secured within a conventional protective splice closure.Moreover, these cable access and splicing steps must typically beaccomplished in the field by a technician who is likely to experiencedifficulties imposed by weather or the particular location of each ofthe drop points. Accordingly, field splicing of drop cables to a maincable is typically time consuming, expensive, and may produce lowquality optical splices.

In an effort to overcome the disadvantages of field splicing drop cablesat each of a series of drop points, so-called preterminated fiber opticcables have been proposed. A preterminated fiber optic cable includes arelatively high fiber count main cable to which respective low fibercount drop cables are spliced at predetermined drop points. Thelocations of the drop points may be determined based upon field surveymeasurements.

The splicing of the drop cables to the main cable of a preterminatedcable is generally performed at the factory during manufacturing of thecable. The preterminated cable, including the main cable, drop cables,and associated splice closures, are desirably wound onto a cable reeland delivered to the installation site. Accordingly, conditions formaking high quality splices may be maximized in the factory, therebypotentially increasing splice quality and also reducing the expense anddifficulty associated with field splicing.

SUMMARY OF THE INVENTION

Embodiments of the present invention include fiber optic cable systems.Such systems include a fiber optic main cable having a strength memberand a plurality of optical fibers extending therein within an outercable sheath. A flexible longitudinally extending inner housing ispositioned proximate the plurality of optical fibers on a section of themain cable having the outer cable sheath removed. The system furtherincludes one or more fiber optic drop cable having at least one opticalfiber having an end portion extending outwardly from an end of the dropcable. The end portion of the at least one optical fiber of said dropcable is spliced together with an end portion of a corresponding atleast one severed end portion of one of the plurality of optical fibersof the main cable to define at least one spliced together fiber portioncoupling at least one of the plurality of optical fibers of the maincable to a corresponding one of the at least one fiber of the dropcable. A longitudinally extending outer protective housing extends overthe section of the main cable having the outer cable sheath removed andthe inner housing and the strength member. The outer protective housinghas a first opening receiving the main cable and a second opening,longitudinally displaced from the first opening, receiving the maincable. At least one of the first opening and the second opening receivethe drop cable. The fiber optic cable system may be a factorypreterminated optical fiber cable having a plurality of drop cablesspliced to the main cable in inner housings positioned at a plurality ofpredetermined longitudinal positions on the cable.

In further embodiments, the inner housing is positioned around theplurality of optical fibers and between the plurality of optical fibersand the strength member and the plurality of optical fibers arepositioned in a central core tube of the main cable longitudinallyextending along a central axis of the main cable. A length of thecentral core tube may be removed in the section of the main cable havingthe outer cable sheath removed so that at least a portion of the atleast one spliced together fiber portion is positioned at a positionradially displaced from the central axis by a distance of no more thanhalf an outer diameter of the central core tube. The at least onespliced together fiber portion may be located so that the at least onespliced together fiber portion is positioned in the inner housing at aposition radially displaced from the central axis by a distance of nomore that about half an outer diameter of the outer sheath.

In other embodiments, the plurality of optical fibers are positioned ina central core tube of the main cable longitudinally extending along acentral axis of the main cable. A length of the central core tube isremoved where the spliced together fiber portion is located so that thespliced together fiber portion is positioned in the inner housing at aposition radially displaced from the central axis by a distance of nomore that about half an outer diameter of the outer sheath. A flexiblelongitudinally extending inner liner may be positioned around the innerhousing and between the inner housing and the strength member. The innerliner has a crush resistance in a radial direction relative to thecentral axis of the main cable greater than a crush resistance of theinner housing.

In further embodiments, the main cable includes a pair of strengthmembers. The pair of strength members is positioned proximatesubstantially opposing sides of the inner strength so that the fiberoptic cable system is more resistant to bending about a first transverseaxis extending between the pair of strength members than along a secondtransverse axis orthogonal to the first transverse axis. A plurality ofprotective housings may be positioned at predetermined positions alongthe main cable and the main cable, with the protective housings thereon,may be wound around a cable spool with the second transverse axisoriented to facilitate wrapping of the main cable around the spool. Theinner liner may be a longitudinally slit polymeric flex conduit. A firstcutout may be provided on each end of the flex conduit that receive andposition a first of the pair of strength members extending therebetweenand a second cutout may be provided on each end of the flex conduitpositioned substantially 180° from the first cutout that receive andposition a second of the pair of strength members extendingtherebetween.

In other embodiments, a greater longitudinal length of the outer sheathis removed than of the central core tube to expose a segment of thecentral core tube at each end of the section of the main cable havingthe outer cable sheath removed. A first attachment member couples afirst end of the inner housing to one of the exposed segments of thecentral core tube and a second attachment member couples a second end ofthe inner housing to the other of the exposed segments of the centralcore tube and couples the drop cable to the main cable. An environmentalsealant may be provided surrounding each of the exposed segments of thecore tube and the environmental sealant and the attachment members maybe positioned in the outer protective housing. The drop cable mayfurther include a buffer tube extending outwardly from the end of thedrop cable with the at least one optical fiber therein and the secondattachment member may couple the buffer tube of the drop cable to thecentral core tube of the main cable. The first and second attachmentmembers may be tie wraps and the environmental sealant may be hot meltadhesive. The outer protective housing may be heatshrink and theplurality of optical fibers of the main cable and the at least oneoptical fiber of the drop cable may be ribbon cables.

In further embodiments, the inner housing includes an inner wallpositioned between the at least one optical fiber of the drop cable andthe at least one spliced together fiber portion and uncut ones of theplurality of optical fibers of the main cable extending across thesection of the main cable having the outer cable sheath removed. Theinner wall has a connector member on a first longitudinally extendingend thereof. A first wrap around outer wall extends from a second end ofthe central wall displaced from the connector member and has a matingconnector member on a second end thereof coupled to the connector memberto define a first chamber around the uncut ones of the plurality ofoptical fibers of the main cable. A second wrap around outer wallextends from the second end of the central wall and has a matingconnector member on a second end thereof coupled to the connector memberto define a second chamber around the at least one optical fiber of thedrop cable and the at least one spliced together fiber portion. Tie-downextension members extend from at least one of the outer walls onlongitudinally displaced ends of the inner housing and extend over theexposed segments of the central core tube. The tie-wraps couple theextension members to the respective exposed segments of the central coretube.

In yet further embodiments, a second fiber optic drop cable having atleast one optical fiber having an end portion extending outwardly froman end of the second drop cable is provided. The end portion of the atleast one optical fiber of the second drop cable is spliced togetherwith an end portion of a corresponding at least one severed end portionof one of the plurality of optical fibers of the main cable within theinner housing to define at least one second spliced together fiberportion coupling at least one of the plurality of optical fibers of themain cable to a corresponding one of the at least one fiber of thesecond drop cable.

In further embodiments, the inner housing includes a longitudinallyextending dividing wall positioned between uncut ones of the pluralityof optical fibers and the at least one spliced together fiber portion. Aflexible longitudinally extending inner liner may be positioned aroundthe inner housing and between the plurality of optical fibers and the atleast one spliced together fiber portion and the strength member. Theinner liner may include positioning surfaces therein configured toreceive the inner housing and may further include guide membersextending laterally therefrom that are configured to receive andposition the strength member extending longitudinally proximate an outersurface of the inner liner.

In yet other embodiments, the inner liner includes a longitudinallyextending first and second segment. The first segment has a connectingmember thereon and the second segment has a mating connecting memberthereon configured to receive the connecting member of the first segmentto couple the first segment and the second segment in a positionextending around the inner housing, the plurality of optical fibers andthe at least one spliced together fiber portion.

In other embodiments, kits for use in factory preterminating at leastone optical fiber of a fiber optic drop cable to a corresponding one ofa plurality of optical fibers extending within an outer cable sheath ofa fiber optic main cable include a flexible longitudinally extendinginner housing configured to be positioned around the plurality ofoptical fibers and between the plurality of optical fibers and astrength member of the main cable on a section of the main cable havingthe outer cable sheath removed and around at least one spliced togetherfiber portion coupling at least one of the plurality of optical fibersof the main cable to a corresponding one of the at least one fiber ofthe drop cable. The kit further includes a longitudinally extendingouter protective housing configured to extend over the section of themain cable having the outer cable sheath removed and the inner housingand the strength member, the outer protective housing having a firstopening configured to receive the main cable and a second opening,longitudinally displaced from the first opening, configured to receivethe drop cable and the main cable. The kits may further include aflexible longitudinally extending inner liner configured to bepositioned around the inner housing and between the inner housing andthe strength member, wherein the inner liner has a crush resistance in aradial direction relative to a central axis of the main cable greaterthan a crush resistance of the inner housing.

In yet further embodiments, methods of factory terminating an opticalfiber cable include determining a number of longitudinally offsetpredetermined termination points to be provided on the optical fibercable, wherein the number is greater than one. A number of tubular outerprotective housings are slid onto the optical fiber cable over a firstend of the optical fiber cable, wherein the number of tubular outerprotective housings is at least equal to the number of terminationpoints. The outer cable sheath is removed from a section of the opticalfiber cable corresponding to a first of the termination points to exposea portion of a fiber protection tube of the optical fiber cable. Alength of the exposed fiber protection tube is removed to expose aplurality of optical fibers of the optical fiber cable. An exposed oneof the plurality of optical fibers is severed. The severed optical fiberof the optical fiber cable is spliced to an optical fiber of anotheroptical fiber cable to provide a splice. One of the tubular outerprotective housings is slid over the section of the optical fiber cablehaving the outer cable sheath removed. The outer protective housing issecured to the optical fiber cable to provide an environmental closurearound the inner housing with the optical fiber cable extending fromrespective longitudinally displaced ends of the outer protective housingand the another optical fiber cable extending from at least one of theends of the outer protective housing.

In other embodiments, the methods of factory terminating an opticalfiber cable further include positioning the splice in a locationproximate the removed length of the exposed fiber protection tube. Aninner housing is positioned around the exposed plurality of opticalfibers of the optical fiber cable and the splice and between theplurality of optical fibers and the splice and an exposed strengthmember of the optical fiber cable. Longitudinally displaced ends of thepositioned inner housing are secured to respective un-removed exposedportions of the fiber protection tube extending from the optical fibercable adjacent the section of the optical fiber cable having the outercable sheath removed. Operations are repeated at additional ones of thepredetermined termination points to splice additional optical fiber dropcables to the optical fiber cable.

In other embodiments, sliding one of the tubular outer protectivehousings into place is preceded by positioning an inner liner around theinner housing and between the inner housing and the strength member. Theouter protective housing may be heatshrink and securing the outerprotective housing may include heating the heatshrink.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an optical fiber cable to bepreterminated according to some embodiments of the present invention;

FIG. 2 is a perspective view of an inner housing of a fiber optic cablesystem according to some embodiments of the present invention on theoptical fiber cable of FIG. 1;

FIG. 3A is a perspective view of the inner housing of FIG. 2 secured tothe optical fiber cable of FIG. 1 according to some embodiments of thepresent invention;

FIG. 3B is a perspective view of a portion of the inner housing shown inFIG. 3A;

FIG. 4A is perspective view of an inner liner of a fiber optic cablesystem positioned over the inner housing of FIGS. 3A and 3B according tosome embodiments of the present invention;

FIG. 4B is a cross sectioned perspective view of the arrangement ofshown in FIG. 4A;

FIG. 5 is perspective view of the arrangement of FIG. 4A withenvironmental sealant on ends thereof according to some embodiments ofthe present invention;

FIG. 6 is a perspective view of a fiber optic cable system according tosome embodiments of the present invention;

FIG. 7 is a flowchart illustrating operations for terminating an opticalfiber according to some embodiments of the present invention;

FIG. 8 is an exploded perspective view of an cable terminationarrangement according to further embodiments of the present invention onthe optical fiber cable of FIG. 1;

FIGS. 9A and 9B are perspective views of the cable terminationarrangement of FIG. 8 with a segment of the inner liner removed and withthe apparatus secured to the optical fiber cable of FIG. 1 according tofurther embodiments of the present invention;

FIG. 10 is a cross sectioned perspective view of the cable terminationarrangement of FIG. 8 according to further embodiments of the presentinvention; and

FIG. 11 is perspective view of the arrangement of FIG. 8 withenvironmental sealant on ends thereof according to further embodimentsof the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which illustrativeembodiments of the invention are shown. In the drawings, the relativesizes of regions or features may be exaggerated for clarity. Thisinvention may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the invention to thoseskilled in the art.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present invention.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90° or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes,” “comprises,”“including” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. It will be understood thatwhen an element is referred to as being “connected” or “coupled” toanother element, it can be directly connected or coupled to the otherelement or intervening elements may be present. Furthermore, “connected”or “coupled” as used herein may include wirelessly connected or coupled.As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Embodiments of the present invention will now be further described withreference to FIGS. 1-6. A termination point of an optical fiber maincable 100 is shown in FIG. 1. The optical fiber main cable 100 is woundaround and extends from a source spool 101. A plurality of protectivehousings, shown as tubular heatshrink sections 111 in FIG. 1, arepositioned on the main cable 100 preparatory to factory terminating theoptical fiber cable 100 according to some embodiments of the presentinvention.

Embodiments of the present invention may provide factory preterminatedoptical fiber cables that may be used, for example, in a factoryinstalled termination system (FITS) and/or Verizon advanced terminationsystem (VATS). Increased flexibility and tolerance to bending inducedstress may be provided by some embodiments, which may allow not only forimproved winding around spools, but installation benefits inapplications requiring, for example, pulling of the cable through ductwork or the like over extended distances. Furthermore, multiple dropcables may be provided exiting from each termination point closure. Inaddition, such systems may be used with both loose and ribbon cablefiber optic systems.

As shown in FIG. 1, the optical fiber cable 100 includes a plurality ofoptical fibers 110, shown as ribbon cable in FIG. 1, extending within acentral core tube 105 a, 105 b, both of which longitudinally extendalong a neutral (relative to bending) or central axis A1 of the cable100. The central core tube 105 a, 105 b and two strength members 108positioned on opposite sides of the central core tube 105 a and 105 b ofthe main cable 100 are surrounded by a protective outer cable sheath 104a, 104 b of the main cable 100. The portion of the cable 100 shown inFIG. 1 corresponds to a termination point, where a slice may be made toform a factory preterminated fiber optic cable system where the cable100 will be the main cable having drop cables spliced thereto at aplurality of longitudinally displaced termination points selected to bepositioned at corresponding locations during installation in the field,such as in a neighborhood or the like.

While shown as including a central core tube 105 a, 105 b in FIG. 1, itwill be understood that the present invention is not limited toembodiments where the main cable 100 is a central core tube type cable.For example, in some embodiments of the present invention, the maincable 100 may be a loose buffer tube type cable including a plurality ofbuffer tubes, wherein the buffer tubes act as fiber protection tubes ina manner substantially similar to the central core tube 105 a, 105 b butdo not extend along a central axis of the cable. In other embodiments, afiber protection tube may not be included in the main cable.

At the illustrated termination point, a section 102 of the main cable100 has the outer cable sheath 104 a, 104 b removed. A length 106 of thecentral core tube 105 a, 105 b is removed in the section 102 to revealthe plurality of optical fibers 110. The strength members 108 are notcut, but extend continuously across the section 102 between the ends 104a and 104 b of the cable 100 adjacent the section 102. The outer sheath104 a, 104 b has a maximum diameter d.

As will be described further herein, the removal of the length 106 ofthe central core tube 105 a, 105 b is contrasted with conventionaltechniques of splicing, where an opening is cut in the central core tube105 a, 105 b without removing the entire central core tube to allowaccess to the optical fibers 110. An improved splice may be provided asa result in some embodiments. More particularly, as will be discussedfurther herein, the removal of the length 106 of the central core tube105 a, 105 b may allow a spliced-together fiber portion to be positionedat a position radially displaced from the central axis A₁ by a distanceof no more than about half the outer diameter d of the outer sheath.Placement of the spliced portion so close to the central axis A₁ mayincrease operational flexibility of the preterminated fiber optic cablesystem by reducing stresses imposed on the splice during bending of thecable 100. It will be understood that the mechanical stress induced inthe longitudinally extending members under flexing are greater thefurther from the neutral axis the splice is located. Furthermore, theclose placement of the splice to the central axis A₁ may allow for alower profile, thinner splice arrangement at the termination point,which may further facilitate rolling of the optical fiber cable 100 ontothe spool 101.

Fiber optic cable systems according to some embodiments of the presentinvention will now be further described with references to FIGS. 2-6. Asshown in FIG. 2, a flexible, longitudinally extending inner housing 210is positioned around the plurality of optical fibers 110 and between theplurality of optical fibers 110 and the strength members 108 and betweenthe plurality of optical fibers 110 and a spliced together fiber portion208 on the section 102 of the main cable 100 having the outer sheathing104 a, 104 b removed. The inner housing 210 may, for example, be awrap-around housing or a multi-piece housing that may be positionedaround the optical fiber cable 100.

A fiber optic drop cable 202 is shown that has a buffer tube 204extending from an end therefrom and at least one optical fiber 206having an end portion extending outwardly from the end of the drop cable202 and buffer tube 204 and into the housing 210. The optical fiber(s)206, like the plurality of optical fibers 110, may be ribbon cables. Theoptical fibers 206 are spliced to a severed end portion 110 a of one ofthe plurality of optical fibers 110 of the main cable 100 within thehousing 210 at the spliced-together fiber portion 208 coupling the maincable 100 and drop cable 202 fiber or fibers.

As best seen in FIGS. 2, 3A, 3B and 4B, the inner housing 210 in theillustrated embodiments includes a central or inner wall 212 positionedbetween the optical fiber 206 and the spliced-together fiber portions208, 408 a, 408 b and uncut ones of a plurality of optical fibers 110 ofthe main cable 100 that extend across the exposed section 102 of themain cable 100. The inner wall 212 has a connector member 218 on a firstlongitudinally extending end thereof.

A first wrap-around outer wall 216 extends from an opposite end of theinner wall 212, displaced from the connector member 218, to define afirst chamber around the uncut ones of the plurality of optical fibers110 of the main cable 100. The first wrap-around outer wall 216 includesa mating connector member 217 on a second end thereof that may becoupled to the connector member 218. A second wrap-around outer wall 214extends from the second end of the central wall 212 and has a matingconnector member 215 on the second end thereof that may be coupled tothe connector member 218 to define a second chamber around the opticalfiber(s) 206 of the drop cable 202 and spliced-together fiber portions208, 408 a, 408 b.

As illustrated in FIG. 4B some embodiments include a plurality ofspliced-together fiber portions 408 a, 408 b that are provided with adividing wall extending transversely from a median portion of the innerwall 212 therebetween so as to provide separate chambers for each of thespliced-together fiber portions 408 a, 408 b. The separatespliced-together fiber portions 408 a, 408 b may be used to splice twoseparate drop cables 202 to the main cable 100 in the inner housing 210or to provide separate splicing of different optical fibers from asingle drop cable 202 or the like.

As further seen in FIGS. 2, 3A and 3B, in some embodiments of thepresent invention, tie-down extension members 220 a, 220 b, 222 a, 222 bmay extend from one or both of the outer walls 214, 216 onlongitudinally displaced ends of the inner housing 210. The extensionmembers 220 a, 220 b, 222 a, 222 b are shown extending over exposedsegments 105 a, 105 b of the central core tube on respective ends of thesection 102 of the cable 100. More particularly, first extension members220 a, 220 b extend from the first outer wall 214 and second extensionmembers 222 a, 222 b extend from the second wrap-around outer wall 216.Note that, as seen in the embodiments of FIG. 2, the inner wall 212extends longitudinally over only a portion of the length 106 where thecentral core tube 105 a, 105 b is removed.

Referring now to FIGS. 3A and 3B, the inner housing 210 is shown securedaround the exposed optical fibers 110 and the spliced-together portion208. More particularly, the inner housing 210 is secured atlongitudinally displaced ends thereof to the respective un-removedexposed portions 105 a, 105 b of the central core tube extending fromthe optical fiber cable 110 on respective ends adjacent to the section106 having the outer cable sheath 104 a, 104 b removed. In particular,the extension members 220 a, 220 b, 222 a, 222 b extending from theouter walls 214, 216 are coupled to the respective exposed segments 105a, 105 b of the central core tube by tie wraps 302 a, 302 b. As bestseen in FIG. 3B, the tie wraps 302 b on one end serve as an attachmentmember coupling the buffer tube 204 of the drop cable 202 to the centralcore tube 105 b of the main cable 100 so as to couple the drop cable 202to the main cable 100. As seen in FIG. 3A, the strength members 108 arepositioned proximate substantially opposing sides of the inner housing210 so that the fiber optic cable system is more resistant to bendingabout a first transverse axis T₁ (FIG. 4A) extending between the pair ofstrength members 108 than along a second transverse axis T₂ orthogonalto the first transverse axis T₁.

Referring now to the embodiments illustrated in FIGS. 4A and 4B, aflexible longitudinally extending inner liner 402 is positioned aroundthe inner housing 210. The inner liner 402 is positioned between theinner housing 210 and the strength members 108. In some embodiments ofthe present invention, the inner liner 402 has a crush resistance in aradial direction relative to the central axis A1 of the main cable 100greater than a crush resistance of the inner housing 210. As illustratedin FIGS. 4A and 4B, the inner liner 402 is a longitudinally slitpolymeric flex conduit. A longitudinal slit, not shown in the figures,may be used to allow passing of the flex conduit over the main cable100. As also shown in FIG. 4A, some embodiments of the present inventioninclude a cut-out 404 a, 404 b on each end of the inner liner 402 thatreceives and positions a strength member 108 extending therebetween.While not visible in FIG. 4A, it will be understood that a correspondingsecond pair of cut-outs are provided in an opposite side of the innerliner 402, positioned substantially 180° from the visible first cut-out404 a, 404 b to receive and position a second of the pair of strengthmembers 108 extending therebetween.

As seen in FIG. 4B, as the length 106 of the central core tube 105 a,105 b has been fully removed, the spliced-together fiber portions 408 a,408 b may be positioned close to the central axis A₁. More particularly,as shown in FIG. 4B, the portions 408 a, 408 b are positioned in theinner housing 210 at a position radially displaced from the central axisA₁ by a distance 406 of no more than about half and outer diameter d ofthe outer sheath 104 a, 104 b. Thus, the splices 408 a, 408 b may bekept close to the neutral central axis A1 to allow bending of thefinished fiber optic cable system at the splice termination pointswithout significant stress to the sliced fibers, as the stress load onthe splice would be expected to increase the greater the distance thesplice point was located from the central axis A₁ of the main cable 100about which flexing would occur during spooling and/or installation ofthe preterminated fiber optic cable system.

Furthermore, in embodiments using the flexible inner liner 402, theliner 402 may resist crushing forces yet still allow the finishedproduct to be flexible during winding on a spool or field installation.Both the inner housing 210 and the inner liner 402 in some embodimentsseparate the cable strength members 108 from the splicing area, suchthat the spliced area may be further protected from disturbance whenflexing occurs during spooling and/or field installation of thepreterminated fiber optic cable system. As also seen in the embodimentsof FIGS. 4A and 4B, the alignment of the strength members 108 outsidethe inner liner 402 may be provided on substantially opposing sides ofthe inner liner 402 so that the fiber optic cable system is moreresistant to bending about the first transverse axis T₁ extendingbetween the pair of strength members 108 than along the secondtransverse axis T₂ orthogonal to the first transverse axis T₁ asdescribed previously with reference to orientation relative to the innerhousing 210.

Referring now to FIG. 5, the arrangement described previously withreference to FIG. 4A is illustrated with the further addition of anenvironmental sealant, shown as hot melt adhesive 502 a, 502 b,surrounding each of the exposed segments 105 a, 105 b of the core tube.After melting of the outer protective housing as will be described withreference to FIG. 6, the hot melt adhesive 502 a, 502 b may also bemelted so as to provide sealing around and between the respective tubes105 a, 105 b, 204 and the strength members 108. Such environmentalsealant may, for example, limit or prevent moisture passing between theouter cable sheath 104 a, 104 b of the main cable 100 and the centralcore tube 105 a, 105 b and/or moisture flowing between the buffer tube204 and the outer protective sheath of the drop cable 202 into thespliced area in the inner housing 210. A moisture flow path mayotherwise be created due to damage to the outer sheath of either themain cable 100 or the drop cable 202, allowing moisture to pass into andrun along the respective cables.

FIG. 6 shows a longitudinally extending outer protective housing 111extending over the section 106 of the main cable 100 having the outercable sheath 104 a, 104 b removed and over the inner housing 210 andinner liner 402 and strength members 108. The protective housing 111 isshown having sufficient length to extend over and engage end portions ofthe outer cable sheath 104 a, 104 b at respective ends of the section106 and to engage the drop cable 202. As such, the outer protectivehousing 111 has a first opening receiving the main cable and engagingthe un-removed portion of the outer cable sheath 104 a and a secondopening, longitudinally displaced from the first opening, receiving andengaging the drop cable 202 and the outer protective sheath 104 b of themain cable 100.

It will be understood that, as generally described with reference toFIG. 1 and the plurality of tubular outer protective housings 111, theplurality of protective housings 111 may be positioned providing anouter protective layer at predetermined positions along the main cable100 and the main cable 100 with the protective housings 111 and enclosedsplices and housings thereon may be wound around a cable spool, such asthe source cable spool 101. The winding of the completed fiber opticcable system with a plurality of preterminated drop cables thereon maybe facilitated by orienting the second transverse axis T₂ (FIG. 4A) soas to facilitate wrapping of the main cable 100 around the spool 101 byhaving the transverse axis T₂ aligned extending radially from the centerof the spool 101 during winding. Thus, a factory preterminated opticalfiber cable having a plurality of drop cables spliced to the main cablein housings positioned at a plurality of predetermined longitudinalpositions on the cable may be provided in some embodiments of thepresent invention.

It will further be understood that other embodiments of the presentinvention provide kits for use in such factory preterminating, where thekits may include an inner housing, an inner liner, and/or an outerprotective housing for use at each termination point.

Methods of factory terminating an optical fiber cable according to someembodiments of the present invention which may allow the use of tubularheatshrink, rather than wrap around sleeves will now be described withreference to the flowchart illustration of FIG. 7. As seen in FIG. 7,operations begin at Block 700 by determining a number of longitudinallyoffset predetermined termination points to be provided on the opticalfiber cable. A number of tubular outer protective housings 111 are slidonto the optical fiber cable over a first end of the optical fibercable, where the number of tubular outer protective housings is at leastequal to the number of termination points (Block 705).

The outer cable sheath is removed from a section of the optical fibercable corresponding to a first of the termination points to expose astrength member and a central core tube (Block 710). A length of theexposed central core tube is removed to expose a plurality of opticalfibers of the optical fiber cable (Block 715). An exposed one of theplurality of optical fibers is severed (Block 720). The severed opticalfiber of the optical fiber cable is spliced to an optical fiber of anoptical fiber drop cable to provide a splice (Block 725). The splice ispositioned in a location proximate the optical fiber cable from wherethe length of the exposed central core tube was removed (Block 730).

An inner housing is positioned around the exposed plurality of opticalfibers of the optical fiber cable and the splice and between theplurality of optical fibers and the splice and the exposed strengthmember (Block 735). Longitudinally displaced ends of the positionedinner housing are secured to respective un-removed exposed portions ofthe central core tube extending from the optical fiber cable adjacentthe section of the optical fiber cable having the outer cable sheathremoved (Block 740). In some embodiments of the present invention,operations at Block 740 may further include positioning an inner lineraround the inner housing and between the inner housing and the strengthmember. One of the tubular outer protective housings is slid over thesection of the optical fiber cable having the outer cable sheath removed(Block 745). The outer protective housing is secured to the opticalfiber cable to provide an environmental closure around the innerhousing, with the optical fiber cable extending from respectivelongitudinally displaced ends of the outer protective housing and theoptical fiber drop cable extending from one of the ends of the outerprotective housing (Block 750). In some embodiments of the presentinvention, the outer protective housing is heatshrink and operations atBlock 750 include heating the heatshrink.

If more splices are to be factory terminated on the optical fiber cable(Block 755), the operations at Blocks 715-750 may be repeated for eachof the respective termination points. It will be understood that, duringrepeated operations, the optical fiber cable may be unwound from thesource spool 101 (FIG. 1) to a termination station and then wound onto asecond spool as a factory pre-terminated cable system ready forinstallation in the field.

Fiber optic cable system arrangements according to further embodimentsof the present invention will now be described with references to FIGS.8 through 11. FIG. 8 is an exploded perspective view of a cabletermination arrangement that may be used in the optical fiber cablearrangement shown in FIG. 1 according to some embodiments of the presentinvention. FIGS. 9A and 9B are perspective views of the arrangement ofFIG. 8 with a segment of the inner liner removed and with thearrangement secured to the optical fiber cable of FIG. 1. FIG. 10 is across-sectional perspective view of a cable terminal arrangement of FIG.8. FIG. 11 is a perspective view of the arrangement of FIG. 8 withenvironmental sealant 502 a, 502 b on the ends thereof.

As seen in FIGS. 8 through 11, the cable termination arrangement 800includes an inner housing 810 and a flexible inner liner having a firstsegment 802 a and a second segment 802 b. The inner housing 810 includesa longitudinally extending dividing wall 812 and a partition wall 812′extending from a middle portion thereof on one face of the dividing wall812. As best seen FIG. 9, the inner housing 810 may be located with thedividing wall 812 positioned between uncut ones of the plurality ofoptical fibers 110 and one or more spliced together fiber portion(s)208.

Each of the illustrated inner liner segments 802 a, 802 b shown in theembodiments of FIGS. 8 through 11 include a plurality of connectingmembers 820 and corresponding mating connecting members 822 at spacedlocations along the mating edges of the respective segments 802 a, 802b. The connecting members 820 and mating connector members 822 may beused to couple the first segment 802 a and the second segment 802 b in aposition extending around the inner housing 810, the optical fibers 110and a spliced together fiber portion(s) 208. As shown in the embodimentsof FIGS. 8 through 11, the connecting members 820 are tabs and themating connecting members 822 are receiving slots. The tabs andreceiving slots of the respective segments 802 a, 802 b are positionedso as to align the respective segments 802 a, 802 b at a longitudinalrelationship when coupled together.

As best seen in FIGS. 9A and 9B, the illustrated embodiments of theinner housing 810 is received in the second segment 802 b on positioningsurfaces 840 thereof configured to receive the inner housing 810. Moreparticularly, for the illustrated embodiments in FIGS. 9A and 9B, theinner housing 810 includes positioning tabs 826 extending laterally fromthe dividing wall 812. The tabs 826 provide both lateral positioning forthe inner housing 810 within the segment 802 b and rest on thepositioning surfaces 840 at a predetermined position above thecenterline of the optical fibers 110 extending between the cable ends104 a, 104 b. The reference surfaces 840 may in combination with thetabs 826, among other things, provide for positioning of the dividingwall 812 in close proximity to the centerline of the optical fibers 110so that the spliced together portion(s) 208 may be positioned as closelyto that centerline as possible for advantageous reasons as discussedpreviously with referenced to FIG. 4B.

Also shown in FIGS. 9A, 9B and 10 are guide members 824, 824′. The guidemembers 824, 824′ extend laterally from the inner liner segment 802 band are configured to receive and position the strength member 108extending longitudinally proximate an outer surface of the inner liner802 a, 802 b. It will be understood that, where the cable 100 includes apair of laterally displaced strength members 108, the guide members 824,824′ may be provided on both sides of the inner liner 802 a, 802 b andon each segment thereof, or on only one of the two segments 802 a, 802b. In addition, the guide member 824 shown in FIGS. 9A and 9B differsfrom the guide member 824′ illustrated in FIG. 10 in the inclusion of acurved portion on an end thereof configured to wrap partially around astrength member 108 received therein. In contrast, the guide members824′ shown in FIG. 10 are illustrated as substantially flat surfaceportions with the channels 822 extend through the surface forming theguide member 824′.

Further aspects of the illustrated embodiments in FIGS. 8 through 11will now be described that are best seen in the illustration of FIGS. 9Aand 9B. These additional aspects related to mechanical coupling of theinner liner 802 a, 802 b, a central core tube 805 b and the buffer tube204.

As seen in FIGS. 9A and 9B and FIG. 11, in some embodiments of thepresent invention, longitudinally displaced ends 828 a, 828 b of theinner liner segments 802 a, 802 b extend over the buffer tubes 105 a,105 b. The end portions over the buffer tube 105 a, 105 b are coupledthereto by tie wraps 834, 836 positioned in respective slots 830, 832 inthe end portions 828 a, 828 b. More particularly, as seen in FIGS. 9Aand 9B, the tie wraps 834 connects the inner liner 802 b to the buffertube 105 a, 105 b while the tie wraps 836 further couples the buffertube 204 to the exposed portion 105 b of the central core tube extendingfrom the optical fiber cable end 104 b.

The perspective view of FIG. 11 generally corresponds to the arrangementshown in FIG. 5, but with different embodiments of the inner liner 802a, 802 b and the inner housing 810 as discussed with reference to FIGS.8 through 10. It will be understood that various aspects and advantagespreviously described with reference to the embodiments of FIG. 5likewise apply to the embodiments of FIGS. 8 through 11.

The foregoing is illustrative of the present invention and is not to beconstrued as limiting thereof. Although a few exemplary embodiments ofthis invention have been described, those skilled in the art willreadily appreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe claims. In the claims, means-plus-function clauses are intended tocover the structures described herein as performing the recited functionand not only structural equivalents but also equivalent structures.Therefore, it is to be understood that the foregoing is illustrative ofthe present invention and is not to be construed as limited to thespecific embodiments disclosed, and that modifications to the disclosedembodiments, as well as other embodiments, are intended to be includedwithin the scope of the appended claims. The invention is defined by thefollowing claims, with equivalents of the claims to be included therein.

That which is claimed:
 1. A method of factory terminating an opticalfiber cable, comprising: determining a number of longitudinally offsetpredetermined termination points to be provided on the optical fibercable, wherein the number is greater than one; sliding a number oftubular outer protective housings onto the optical fiber cable over afirst end of the optical fiber cable, wherein the number of tubularouter protective housings is at least equal to the number of terminationpoints; removing the outer cable sheath from a section of the opticalfiber cable corresponding to a first of the termination points to exposea portion of a fiber protection tube of the optical fiber cable;removing a length of the exposed fiber protection tube to expose aplurality of optical fibers of the optical fiber cable; severing anexposed one of the plurality of optical fibers; splicing the severedoptical fiber of the optical fiber cable to an optical fiber of anotheroptical fiber cable to provide a splice; sliding one of the tubularouter protective housings over the section of the optical fiber cablehaving the outer cable sheath removed; and securing the outer protectivehousing to the optical fiber cable to provide an environmental closurearound the section of the optical fiber cable with the optical fibercable extending from respective longitudinally displaced ends of theouter protective housing and the another optical fiber cable extendingfrom at least one of the ends of the outer protective housing.
 2. Themethod of claim 1, wherein splicing the severed optical fiber isfollowed by: positioning the splice in a location proximate the removedlength of the exposed fiber protection tube; positioning an innerhousing proximate and covering the exposed plurality of optical fibersof the optical fiber cable and the splice; securing longitudinallydisplaced ends of the positioned inner housing to respective un-removedexposed portions of the fiber protection tube extending from the opticalfiber cable adjacent the section of the optical fiber cable having theouter cable sheath removed; and repeating removing the outer cablesheath, removing a length of the exposed central core tube, severing anexposed one of the plurality of optical fibers, splicing the severedoptical fiber, splicing the severed optical fiber, positioning thesplice, positioning the inner housing, securing longitudinally displacedends, sliding one of the tubular outer protective housings and securingthe outer protective housing at additional ones of the predeterminedtermination points with an inner housing therein to splice additionaloptical fiber cables to the optical fiber cable.
 3. The method of claim2, wherein positioning the inner housing comprises positioning the innerhousing around the exposed plurality of optical fibers of the opticalfiber cable and the splice and between the plurality of optical fibersand the splice and an exposed strength member of the optical fibercable.
 4. The method of claim 1, wherein sliding one of the tubularouter protective housings is preceded by: positioning an inner housingcovering the exposed plurality of optical fibers of the optical fibercable and the splice; and positioning an inner liner around the innerhousing and between the inner housing and an exposed strength member ofthe optical fiber cable.
 5. The method of claim 1, wherein the outerprotective housing comprises heatshrink and wherein securing the outerprotective housing comprises heating the heatshrink.